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  • OpenGL Performance Questions

    - by Daniel
    This subject, as with any optimisation problem, gets hit on a lot, but I just couldn't find what I (think) I want. A lot of tutorials, and even SO questions have similar tips; generally covering: Use GL face culling (the OpenGL function, not the scene logic) Only send 1 matrix to the GPU (projectionModelView combination), therefore decreasing the MVP calculations from per vertex to once per model (as it should be). Use interleaved Vertices Minimize as many GL calls as possible, batch where appropriate And possibly a few/many others. I am (for curiosity reasons) rendering 28 million triangles in my application using several vertex buffers. I have tried all the above techniques (to the best of my knowledge), and received almost no performance change. Whilst I am receiving around 40FPS in my implementation, which is by no means problematic, I am still curious as to where these optimisation 'tips' actually come into use? My CPU is idling around 20-50% during rendering, therefore I assume I am GPU bound for increasing performance. Note: I am looking into gDEBugger at the moment Cross posted at StackOverflow

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  • OpenGL-ES: clearing the alpha of the FrameBufferObject

    - by MrDatabase
    This question is a follow-up to Texture artifacts on iPad How does one "clear the alpha of the render texture frameBufferObject"? I've searched around here, StackOverflow and various search engines but no luck. I've tried a few things... for example calling GlClear(GL_COLOR_BUFFER_BIT) at the beginning of my render loop... but it doesn't seem to make a difference. Any help is appreciated since I'm still new to OpenGL. Cheers! p.s. I read on SO and in Apple's documentation that GlClear should always be called at the beginning of the renderLoop. Agree? Disagree? Here's where I read this: http://stackoverflow.com/questions/2538662/how-does-glclear-improve-performance

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  • "Unable to create OpenGL 3.3 context (flags 0, profile 1)"

    - by Tsvetan
    Trying to run any of the well-known McKesson's tutorials on a friend's laptop results in the aforementioned exception. I read that in order to run applications which use OpenGL 3.3 you must at least have an ATI HD or Nvidia 8xxx GPU series. He has an ATI HD class graphics processor which eliminates (maybe) this issue. Also, I read that this error may result in having old drivers. He updated his drivers but that didn't solve the problem. The tutorials are built as said in the book introduction and glsdk is installed. If more information is needed, say so and I will provide it. What are the other reasons for this kind of exception? And how can I fix them?

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  • Timing Calculations for Opengl ES 2.0 draw calls

    - by Arun AC
    I am drawing a cube in OpenGL ES 2.0 in Linux. I am calculating the time taken for each frame using below function #define NANO 1000000000 #define NANO_TO_MICRO(x) ((x)/1000) uint64_t getTick() { struct timespec stCT; clock_gettime(CLOCK_MONOTONIC, &stCT); uint64_t iCurrTimeNano = (1000000000 * stCT.tv_sec + stCT.tv_nsec); // in Nano Secs uint64_t iCurrTimeMicro = NANO_TO_MICRO(iCurrTimeNano); // in Micro Secs return iCurrTimeMicro; } I am running my code for 100 frames with simple x-axis rotation. I am getting around 200 to 220 microsecs per frame. that means am i getting around (1/220microsec = 4545) FPS Is my GPU is that fast? I strongly doubt this result. what went wrong in the code? Regards, Arun AC

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  • Vertex Array Object (OpenGL)

    - by Shin
    I've just started out with OpenGL I still haven't really understood what Vertex Array Objects are and how they can be employed. If Vertex Buffer Object are used to store vertex data (such as their positions and texture coordinates) and the VAOs only contain status flags, where can they be used? What's their purpose? As far as I understood from the (very incomplete and unclear) GL Wiki, VAOs are used to set the flags/status for every vertex, following the order described in the Element Array Buffer, but the wiki was really ambiguous about it and I'm not really sure about what VAOs really do and how I could employ them.

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  • Translating an Object to a certain Vector 3 in OpenGL and Java LWJGL

    - by aliasmk
    So after almost two hours, I got the hang of using glTranslated() (with Java and LWJGL). If I am correct, applying glTranslated on an object moves that object with the x,y,z relative to the previously moved object. I believe the correct term for this is local vs global, global being the one I want. I was wondering if there was a way to translate an object to a specific XYZ position, or relative to the origin. Thanks! (Code or other details can be supplied if it helps, just let me know. Also sorry if this is a noob comment, Im very new to OpenGL.)

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  • OpenGL: Filtering/antialising textures in a 2D game

    - by futlib
    I'm working on a 2D game using OpenGL 1.5 that uses rather large textures. I'm seeing aliasing effects and am wondering how to tackle those. I'm finding lots of material about antialiasing in 3D games, but I don't see how most of that applies to 2D games - e.g. antisoptric filtering seems to make no sense, FSAA doesn't sound like the best bet either. I suppose this means texture filtering is my best option? Right now I'm using bilinear filtering, I think: glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); From what I've read, I'd have to use mipmaps to use trilinear filtering, which would drive memory usage up, so I'd rather not. I know the final sizes of all the textures when they are loaded, so can't I somehow size them correctly at that point? (Using some form of texture filtering).

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  • Lwjgl or opengl double pixels

    - by Philippe Paré
    I'm working in java with LWJGL and trying to double all my pixels. I'm trying to draw in an area of 800x450 and then stretch all the frame image to the complete 1600x900 pixels without them getting blured. I can't figure out how to do that in java, everything I find is in c++... A hint would be great! Thanks a lot. EDIT : I've tried drawing to a texture created in opengl by setting it to the framebuffer, but I can't find a way to use glGenTextures() in java... so this is not working... also I though about using a shader but I would not be able to draw only in the smaller region...

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  • OpenGL Shading Program Object Memory Requirement

    - by Hans Wurst
    gDEbugger states that OpenGL's program objects only occupy an insignificant amount of memory. How much is this actually? I don't know if the stuff I looked up in mesa is actually that I was looking for but it requires 16KB [Edit: false, confusing struct names, less than 1KB immediate, some further behind pointers] per program object. Not quite insignificant. So is it recommended to create a unique program object for each object of the scene? Or to share a single program object and set the scene's object's custom variables just before its draw call?

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  • Beginner question about vertex arrays in OpenGL

    - by MrDatabase
    Is there a special order in which vertices are entered into a vertex array? Currently I'm drawing single textures like this: glBindTexture(GL_TEXTURE_2D, texName); glVertexPointer(2, GL_FLOAT, 0, vertices); glTexCoordPointer(2, GL_FLOAT, 0, coordinates); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); where vertices has four "xy pairs". This is working fine. As a test I doubled the sizes of the vertices and coordinates arrays and changed the last line above to: glDrawArrays(GL_TRIANGLE_STRIP, 0, 8); since vertices now contains eight "xy pairs". I do see two textures (the second is intentionally offset from the first). However the textures are now distorted. I've tried passing GL_TRIANGLES to glDrawArrays instead of GL_TRIANGLE_STRIP but this doesn't work either. I'm so new to OpenGL that I thought it's best to just ask here :-) Cheers!

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  • Basics of drawing in 2d with OpenGL 3 shaders

    - by davidism
    I am new to OpenGL 3 and graphics programming, and want to create some basic 2d graphics. I have the following scenario of how I might go about drawing a basic (but general) 2d rectangle. I'm not sure if this is the correct way to think about it, or, if it is, how to implement it. In my head, here's how I imagine doing it: t = make_rectangle(width, height) build general VBO, centered at 0, 0 optionally: t.set_scale(2) optionally: t.set_angle(30) t.draw_at(x, y) calculates some sort of scale/rotate/translate matrix (or matrices), passes the VBO and the matrix to a shader program Something happens to clip the world to the view visible on screen. I'm really unclear on how 4 and 5 will work. The main problem is that all the tutorials I find either: use fixed function pipeline, are for 3d, or are unclear how to do something this "simple". Can someone provide me with either a better way to think of / do this, or some concrete code detailing performing the transformations in a shader and constructing and passing the data required for this shader transformation?

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  • OpenGL error LNK2019

    - by Ghilliedrone
    I'm trying to compile a basic OpenGL program. I linked opengl32.lib and glu32.lib but I'm getting errors. The errors I get are: error LNK1120: 7 unresolved externals error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup error LNK2019: unresolved external symbol "public: float __thiscall GLWindow::getElapsedSeconds(void)" (?getElapsedSeconds@GLWindow@@QAEMXZ) referenced in function _WinMain@16 error LNK2019: unresolved external symbol "public: bool __thiscall GLWindow::isRunning(void)" (?isRunning@GLWindow@@QAE_NXZ) referenced in function _WinMain@16 error LNK2019: unresolved external symbol "public: void __thiscall GLWindow::attachExample(class Example *)" (?attachExample@GLWindow@@QAEXPAVExample@@@Z) referenced in function _WinMain@16 error LNK2019: unresolved external symbol "public: void __thiscall GLWindow::destroy(void)" (?destroy@GLWindow@@QAEXXZ) referenced in function _WinMain@16 error LNK2019: unresolved external symbol "public: __thiscall GLWindow::GLWindow(struct HINSTANCE__ *)" (??0GLWindow@@QAE@PAUHINSTANCE__@@@Z) referenced in function _WinMain@16 error LNK2019: unresolved external symbol "private: void __thiscall GLWindow::setupPixelFormat(void)" (?setupPixelFormat@GLWindow@@AAEXXZ) referenced in function "public: long __stdcall GLWindow::WndProc(struct HWND__ *,unsigned int,unsigned int,long)" (?WndProc@GLWindow@@QAGJPAUHWND__@@IIJ@Z)

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  • Android how to get opengl 3D coordinates in ontouch event

    - by Sandy
    I created a cube in opengl and it rotates in ontouch event. To to this I created a CustomSurfaceView as follows public class CustomSurfaceView extends GLSurfaceView { @Override public boolean onTouchEvent(MotionEvent e) { float x = e.getX() float y = e.getY(); } } Here x and y are screen coordinates. How can I get 3D coordinated from this? I have already looked gluProject and NeHe. But I dont know how to implement this in my project, it shows that there is no GLdouble,GLfloat class.

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  • Displaying and updating score in Android (OpenGL ES 2)

    - by user16547
    I'm using a FrameLayout where I have a GLSurfaceView at the bottom and a few Views on top of it. One of those Views is a TextView that displays the current score. Here's how I'm updating the score TextView based on what happens in my game loop: whenever an event happens that increases the score, I call activity.runOnUiThread(updater), where activity is the activity that has the above FrameLayout (my main game activity) and updater is just a Runnable that increments the score. From my understanding, using runOnUiThread() from the OpenGL thread is standard practice - otherwise you'll get an exception, I can't remember its name. The problem is that there's a very noticeable lag between the event and the score update. For example the character gets a coin, but the coin count is not updated quickly. I tried summing all the score events from my game loop and calling runOnUiThread() only once per loop, but it doesn't seem to make much of a difference - the lag is still noticeable. How can I improve my design to avoid this lag?

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  • openGL Camera setup for Zoom in/out centered at point under cursor

    - by user3228921
    I am trying to implement a zoom in/out navigation mode in a openGL 3dViewer. I was able to implement zoom functionality centered at screen center just by moving eye towards the center in perspective mode. Now i am trying to do the zoom centered at arbitrary position under the cursor. I am unable to figure out how should i move my camera forward and backward such that point under cursor remains at the same screen coordinates after zoom in/out. Any help would be appreciated. Below are the images which show the desired effect. Just to mention, I am working in a perspective mode with eye target and up vectors to control camera. Same effect i found in google sketchup and 'zoom to mouse position' setting in blender.

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  • OpenGL Vertex Attributes - Normalisation

    - by Daniel
    Alas, I have searched, and have found no definitive answer. When would you normalize the vertex data in OpenGL using the following command: glVertexAttribPointer(index, size, type, normalize, stride, pointer); I.e when would normalize == GL_TRUE; what situations, and why would you choose to let the GPU do the calculations instead of preprocessing it? All examples I have ever seen, have this set to GL_FALSE; and I cannot personally see a use for it. But Khronos aren't stupid, so it must be there for something useful (and probably common).

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  • OpenGL Drawing textured model (OBJ) black texture

    - by andrepcg
    I'm using OpenGL, Glew, GLFW and Glut to create a simple game. I've been following some tutorials and I have now a good model importer with textures (from ogldev.atspace.co.uk) but I'm having an issue with the model textures. I have a skybox with a beautiful texture as you can see in the picture That weird texture behind the helicopter (model) is the heli model that I've applied on purpose to that wall to demonstrate that specific texture is working, but not on the helicopter. I'll include the files I'm working on so you can check it out. Mesh.cpp - http://pastebin.com/pxDuKyQa Texture.cpp - http://pastebin.com/AByWjwL6 Render function + skybox - http://pastebin.com/Vivc9qnT I'm just calling mesh->Render(); before the drawSkyBox function, in the render loop. Why is the heli black when I can perfectly apply its texture to another quad? I've debugged the code and the mesh-render() call is correctly fetching the texture number and passing it to the texture-bind() function.

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  • OpenGL ES 2.0 gluUnProject

    - by secheung
    I've spent more time than I should trying to get my ray picking program working. I'm pretty convinced my math is solid with respect to line plane intersection, but I believe the problem lies with the changing of the mouse screen touch into 3D world space. Heres my code: public void passTouchEvents(MotionEvent e){ int[] viewport = {0,0,viewportWidth,viewportHeight}; float x = e.getX(), y = viewportHeight - e.getY(); float[] pos1 = new float[4]; float[] pos2 = new float[4]; GLU.gluUnProject( x, y, 0.0f, mViewMatrix, 0, mProjectionMatrix, 0, viewport, 0, pos1, 0); GLU.gluUnProject( x, y, 1.0f, mViewMatrix, 0, mProjectionMatrix, 0, viewport, 0, pos2, 0); } Just as a reference I've tried transforming the coordinates 0,0,0 and got an offset. It would be appreciated if you would answer using OpenGL ES 2.0 code.

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  • Detailed Modern Opengl Tutorial?

    - by Kogesho
    I am asking for a specific modern opengl tutorial. I need a tutorial that does not skip to explain any lines of code. It should also include different independent objects moving/rotating (most tutorials use only one object), as well as imported 3d objects and collision detection for them. It should also avoid stuff that won't be used. Arcysnthesis for example gives a new concept, and after teaching it, in the next tutorial, it explains how bad it is for performance and introduces another method. Do you know any?

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  • What is a right datatype in C++ for OpenGL scene representation with use of GLSL

    - by Rarach
    I am programming in C++ OpenGl with GLSL. Until now I have been using a data structure that is composed of std::vector filled with structures of vertexes and with their parameters (position , normal, color ...) as a global variable for all the code. My question is, as I am using VBOs for drawing - is this a good approach to this problem? I am asking because I happen to have a lot of memory related trouble with this structure. I am trying to generate a terrain with a lot of vertices - more than 1 million. This seems to work, but as I refill the buffer I get memory related issues (crushes that occur, more or less randomly). So again the question is, is this a good data structure to use / and look for the faults in my code, or should I change to something else? Or what data structure would be advisable?

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  • Per fragment lighting with OpenGL 4.x tessellated model

    - by Finlaybob
    I'm experienced with OpenGL 3+. I'm dabbling with tessellation shaders and have now got to a point where I have a nicely tessellated teapot/plane demo (quick look here) As can be seen from the screenshots, the lighting is broken (though admittedly doesn't look too bad in the image) I've tried to add a normal map to the equation but it still doesn't come out right, I can calculate the normals, tangents and binormals per triangle in the geometry shader but still looks wrong. I think the question would be; How do I add per fragment lighting to a tessellated model? The teapot is 32 16-point patches, the plane is one single 16 point patch. The shaders are here, but they are a complete mess, so I don't blame anyone who cant make sense of them. But peruse at your leisure if you like. Also, if this question is more suited to be somewhere else i.e. Stack Overflow or the Programming stack please let me know.

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  • Drawing application on OpenGL for iOS (iPad)

    - by Alesia
    Some help is needed. I'm developing drawing application on OpenGL (deployment target 4.0) for iOS (iPad). We have 3 drawing tools: pen, marker (with alfa) and eraser. I draw with textures, using blending in orthographic projection. I can't use z-ordering because in this case I have to face a lot of troubles with cutting and erasing. The thing that I need is to make the pen be always on the top. When I first use marker and than pen - it's ok. But if I use pen first and marker over the pen - I can't see pen color under marker. I'd appreciate any help or advice. Thank you veeeeeery much!

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  • Unity3D or UDK or OPENGL from scratch?

    - by Legolas
    I am just very confused which I should choose in terms of high end game development. The application that I am designing is pretty simple, requires some 3D, and some effects. I am looking at a game similar to ping pong, but with high textures and graphics. I will just need web services to submit high scores. From my description, you can see that its pretty straight forward and I am confused whether I should use Unity3D or UDK or write the entire application myself with openGL (which will take a lot of time though). If you had faced this dilemma before, and chose for a particular graphics engine, please provide your suggestions and reasons as to why that was better. It would be helpful. Also, how can this affect in terms of investment and revenue ?

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  • OpenGL ES 2.0. Sprite Sheet Animation

    - by Project Dumbo Dev
    I've found a bunch of tutorials on how to make this work on Open GL 1 & 1.1 but I can't find it for 2.0. I would work it out by loading the texture and use a matrix on the vertex shader to move through the sprite sheet. I'm looking for the most efficient way to do it. I've read that when you do the thing I'm proposing you are constantly changing the VBO's and that that is not good. Edit: Been doing some research myself. Came upon this two Updating Texture and referring to the one before PBO's. I can't use PBO's since i'm using ES version of OpenGL so I suppose the best way is to make FBO's but, what I still don't get, is if I should create a Sprite atlas/batch and make a FBO/loadtexture for each frame of if I should load every frame into the buffer and change just de texture directions.

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  • How do I create a fire sphere (fireball) in opengl? (opengl Visual C++)

    - by gn66
    I'm making an evil Pacman in OpenGL and I need to make my spheres look like a fireballs, does anyone know how I do that? And what material colour should I use? Also, is there a colour palette to change the colour of my materials? This is how I create a sphere: GLfloat mat_ambient[] = { 0.25, 0.25, 0.25, 1.0 }; GLfloat mat_diffuse[] = { 0.4, 0.4, 0.4, 1.0 }; GLfloat mat_specular[] = { 0.774597, 0.774597, 0.774597, 1.0 }; GLfloat mat_shine = 0.6; glMaterialfv (GL_FRONT, GL_AMBIENT, mat_ambient); glMaterialfv (GL_FRONT, GL_DIFFUSE, mat_diffuse); glMaterialfv (GL_FRONT, GL_SPECULAR, mat_specular); glMaterialf (GL_FRONT, GL_SHININESS, mat_shine * 128); glPushMatrix(); glTranslatef(x,y,0); glutSolidSphere(size, 20, 10); glFlush(); glPopMatrix();

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